Steam generating apparatus and method



STEAM GENERATING APPARATUS AND METHOD File J. May 20, 924- 4 Sheets-Sheet 1 5 Elvwemtoz I CH/IRL 55E GKADK} Oct. 2, 1934.

c. GRADY STEAM GENERATING APPARATUS AND METHOD Filed May '20. 1924 4 Sheets-Sheet 2 nniiiiiiiinirj o o o 0 c o o e o o c 0 o ooo'oooo cnaoooaooo oooonoooonooooo '11 III! will I'll/l1 IV/Il/ ray/I11 III/III) I WININININIWI Svwemtoz CHARLESB GKADK 4 Sheets-Sheet 3 Svweutoz CHAKLESE GKADY (l t tom:

C. B. GRADY STEAM GENERATING APPARATUS AND METHOD Filed May 20, 1924 II 6 {SE a iv IILF mi lllLr m Oct. 2, 1934. ,c. B.-GRADY 1,975,268

v STEAM GENERATING APPARATUS AND METHOD Filed May 20. 1924 4 Sheets-Sheet 4 Elwuembm:

Patented Oct. 2, 1934 UNITED STATES PATENT OFFICE METH Charles B. Grady, West Orange, N. J assignor to Metropolitan Engineering Company, a corporation of New York Application May 20, 1924, Serial No. 714,535

20 Claims.

My present application is a continuation in part of my application for a Method of and apparatus for generating steam filed September 28, 1923, Serial No. 665,266 patented May 30, 1933, Patent No. 1,911,501. While not limited thereto, the method and apparatus herein disclosed is particularly adapted for burning pulverized fuel, blastfurnace gas, oil, tar and similar fuels. The invention will be understood from the following specification when read in connection with the accompanying drawings which illustrate a steam generating unit embodying various features of the invention which are pointed out with particularity in the appended claims. In the drawings:-

Fig. 1 is a longitudinal vertical section taken along lines 11 of Figs. 2 and 3;

Figs. 2 and 3 are vertical cross-sections taken respectively along the lines 2-2 and 3-3 of Fi 1;

Fig. 4 is a Vertical section through a wall panel of the main furnace;

Fig. 5 is a fragmentary view of the wall panel looking from inside of main furnace;

Fig. 6 is a part view of wall panel looking from outside of main furnace;

Fig. 7 is a vertical section through an oven wall;

Fig. 8 is a partial bottom view of an oven wall;

Fig. 9 is a vertical part section through the air heater and dust catcher on the right side of Fig. 1.

Fig. 10 illustrates a modified arrangement embodying features of my invention.

Referring to the embodiment of the invention illustrated, the powdered coal or other fuel and air passes downwardly through nozzles 10 in a top wall 11 into a chamber 1 which I call an oven, where the fuel will be dried and'ignited so as to give it a good start toward combustion. This is bounded by end walls 12, Fig. 1, and side walls 13, Fig. 2. The walls 12 and 13 of the oven 1 are composed of blocks of refractory material 14 hung from structural members 15 by means of pipes 16, as shown in detail in Figs. 7 and 8. Air is admitted to the top of the prefurnace 17 through said pipes 16 thus cooling the oven walls 12 and 13. The bottom of the oven 1 is open and communicates with a chamber 1'7 which I call a pre-furnace, having end walls 18 and parallel side walls formed by wall panels 19. The end walls 18 of the pre-furnace are rounded outwardly at their lower ends where the chamber 1'7 communicates with a chamber 2 which is of very much enlarged size in the endwise direction and which I call the main furnace. This is bounded on the sides by wall panels 8 and superheaters 22, at one end by a wall panel 21 and at the other end by a super- 0 heater 29.

The bottom 23 of the main furnace 2 is provided with a number of compartments 24 connecting to the bottom 23 by means of openings 25. These compartments connect at one end into a trough 26, Figs. 2 and 3, the other ends of the compartments being provided with water pipes 2'7. The ash and slag in the bottom of the furnace falls through openings 25 to compartments 24, and is washed through compartments 24 by means of water from pipes 27 into trough 26 which may be led to any convenient place. Bottom 23 of main furnace 2 is provided with four curb walls 28.

The burning mixture passes downwardly from the oven 1 through the pre-furnace 17, entering the top of main furnace 2 where it divides into two streams, one stream curving to the right and upwardly and passing by a radiant heat superheater 22, Fig. 1, the other stream curving toward the left and upwardly and passing by a radiant heat superheater 29, Fig. 2. Each gas stream comprising the products of combustion formed by the burning mixture then passes upwardly through a boiler 3, then through a vertical passage 31, then through an economizer 5, thence through an elbow 51 and thence through a combination air heater and dust catcher 6, being drawn therefrom through duct 60 by a fan 61 which discharges them through a passage 62 into a gas washer '7 comprising a vertical duct 70 with an inclined wall down which a film of water is passing and thence over a body of water accumulated in the bottom of the washer, each gas washer '7 discharging into a chamber '71 which may lead by exit port 71a to a stack or chimney. Superheater 29, Fig. 2, is bent around so as to form the roof of a small oven 9, Fig. 1, opening into the end of the main furnace. Oven 9 is provided with side walls 91, bottom 92, and end walls 93. Side walls 91 of .the oven 9 are provided with doors 99.

Auxiliary nozzles 94 are provided in the end wall 93 of the oven 9 and in the wall panel 21 of the main furace on the opposite side from the oven 9. These auxiliary nozzles 94 deliver powdered coal or other fuel, together with the necessary air for combustion, into the oven 9 and main furnace 2 near superheaters 22 and 29. The

total heating surface of the superheaters 22 and 29 may be proportioned so that the superheated steam coming from them will'not exceed a certain desired temperature under certain operating conditions with the tubes clean and with auxiliary nozzles running light. It is a well known fact that with such a design, superheat will fall off under different operating conditions, as the dirt and dust gathers on the tubes. The function of the auxiliary nozzles 94 is to prevent said falling off in superheat, and by their use I provide a simple, reliable, economical method of maintaining a substantially constant superheat.

The above described method and apparatus for supplying auxiliary heat to supplement the superheating elements placed in the furnace wall is not limited to a furnace fired by powdered coal, gas or oil, but may be used in any furnace such as av furnace fired by a stoker.

Referring to Figs. 1, 2, 4, 5 and 6, the wall panel 8 is composed of water carrying tubes 81, spaced close together or abutting each other, a metallic casing 82, metallic ties 83, welded to said tubes 81 and bolted to said casing 82, a heat insulating material 84 filling the space between said casingand said tubes, and an upper water carrying header 85 and a lower water carrying header 86, thus constituting a composite water cooled wall panel. The upper header 85 rests upon the upper portion of the supporting girder 87. A horizontal structural steel member 88 is provided to prevent said composite wall from moving horizontally. This construction, therefore, gives us a furnace wall which is hung somewhat like a curtain, free to expand and contract, light in weight and substantially impervious to air filtration. Tubes 81 may be spot-welded together by welds 89. superheater 22 is of the same construction as described above.- Wall panels 21 and wall panels 19 are also composed of the same construction as described above. The end walls 18 of the pre-furnace are also of the samegeneral construction as described above,

except that they have no upper header, the walls being hung from the drums, and no lower header as the tubes 36 are bent around, being spaced apart beyond the bend to allow the gases to go up through the boiler.

The above described furnace wall construction is not limited to a furnace fired by powdered coal, gas or oil, but may be used in any furnace such as a furnace fired by a stoker.

Each boiler 3, Fig. 1 comprises a plurality of downcomer tubes 32 leading from the bottom of drum 33 to the top of a plurality of horizontal tubes 34 connected together by return bends 35 so that the water flows serially in a downward direction, back and forth, and on one side of steam generating unit discharging into tubes 36, where the wet steam is exposed to the heat in the pre-furnace, and then upward to the drum 33, and on the left side of the steam generating unit discharging into a header 37, thence to downcomer 38, thence to the header 86 and wall panel 8, thence upwardly through said wall panel, thence still upwardly through uptake 39 to the boiler drum 33.

Water is delivered to the wall panel 21 of the main furnace from the drum 33 on the right side of the steam generating unit, Fig. l, by means of downcomers 49 and 40, and returns by means of uptake 41. 7

Water is delivered to the wall panels 19 of the pre-furnace from the drums 33 by means of downcomers 49, and returns by way of elbows 56.

One boiler 3 as shown on the right side of Fig.

1 is provided with a drain header 30, commonly called a mud drum.

The flow through the superheater 22 on the right side of my steam generating unit as shown on Fig. 1 is as follows:

From drum 33 through pipe 42 to horizontal header 44, thence downwardly through tubes 43 of superheater 22 to horizontal header 45, from which the steam may be led to any convenient place.

The flow through the superheater on the other side of my steam generating unit, namely the left-hand side, Fig. 1 is as follows:

From the drum 33 through pipe 46 to horizontal header 4'7, thence through tubes 100 of superheater 29 to horizontal header 48, from which the steam may be led to any convenient place.

The different arrangements of water carrying surfaces and superheating surfaces as described above may be combined in various ways, and I do not wish to limit myself to the specific combination shown on the drawings; for instance, superheater 22 might be used to superheat steam coming from a high pressure turbine and going to a low pressure turbine, the steam from both drums 33 being led to superheater 29, said superheater being proportioned to properly superheat the steam for the entire steam generating unit.

Economizer 5 is composed of a bank of tubes 50, and return bends 52. The water enters said economizer from a pipe 53 into a header 54, thence into the top tube bank composed of tubes 50, thence through said tubes 50 and return bends 52 to tubes 55 and thence to downcomer tubes 32, the water flowing serially in a downward direction, back and forth, each tube section finally delivering the boiler feed water directly into the boiler circulatory system at a position and in a direction so that the circulation will be augmented.

The comparatively long length of the downcomer tubes 32, each of which will carry a heavy column composed entirely of water, or of water with a slight percentage of steam, and the comparative long length of the vertical portion of the tubes 36 which being exposed to the intense heat of the burning mixture in the pre-furnace, will contain a light column composed of Water with a large percentage of steam, tend further to substantially augment said circulation and make it sound, rapid and positive.

I do not, however, wish to limit myself to the use of the serial boiler above described for a standard type of boiler such as may be used in connection with my steam generating method and apparatus herein claimed.

The application to my apparatus of such a standard or known type of boiler is illustrated in Fig. 10. In this figure the two-upper drums 102 and 103 of the boiler are connected with a'single lower drum 104 by the tube banks 105 and 106.

The other parts of the apparatus are substantially identical with parts shown in the other views and are identified by the corresponding reference characters, and the arrows indicate the path of the gases through the apparatus.

Combination air heater and dust catcher 6 comprises two horizontal ducts, the lower one 63 being for the gas, and the upper one 64 for the air. the two ducts being separated by horizontal partition 65, a plurality of vertical heat exchanger tubes 66, a number of compartments 67 formed by vertical partition 98 below the bottoms of the heat exchanger tubes. For the air heater and dust catcher shown on the right-hand side of my steam generating unit, Fig. 1, the lower portions of the compartments'67 are formed by the bottom 68 of the air heater and dust catcher 6.

On the other side of my steam generating unit, 5 that is the left-hand side, shown on Fig. -1, the bottoms of the compartments 6'? are formed by the upper surface of a body of water 69. The heat exchanger tubes 66 are shown in detail in Fig. 9, and I prefer to have each tube partially filled with a liquid 101 and the air exhausted therefrom and the tube hermetically sealed as shown and described in my application for Steam rating apparatus and method, filed September 28, 1923, SerialNoT665j266f The gases entering the combination air heater and. dust catcher 6 having passed through the economizer will be at a moderate temperature, say for instance, 275 Fahrenheit, and the gases will come in contact with the heat exchanger tubes 66 evaporating the liquid therein (giving heat thereto) the vapor rising to the upper ends of the tubes condensing and giving heat to the air. The solid particles entrained in the gases will come in contact with and impinge upon the heat exchanger tubes 66, some of said particles collecting on the tubes, and a substantial portion will drop down into the compartments 67 or water 69, and be deposited therein. The vertical partitions 98 dividing the lower portion of the air heater and dust catcher 6 into the several compartments 6'7, aid in the deposition of the solid particles.

The air for combustion is delivered to air heater and dust catcher 6 by means of a fan 95 and elbow 96 and to burners by duct 97.

The above described air heater and dust catcher 6 is not limited to the cleaning of boiler gases and abstracting the heat therefrom and heating air with said heat, but may be used to clean and abstract the heat from the gases or fumes coming from industrial appliances, for example, it can be used for cleaning and abstracting the heat from the gases coming from a blast furnace, the heated air being .used in any desired way.

The major part of the heat absorbing surfaces for the water carrying elements in my prefurnace, main furnace, boiler, economizer and air heater, the heat releasing surface of the air heater and the superheating surface in the main furnace 'and on top of the small oven 9, are composed of plain round tubes which are well adapted for the application of any form of extended surface. The application of extended surfaces would, of course, decrease the amount of round tube area necessary.

The above mentioned surfaces are also well adapted and conveniently arranged for the application of any desired form of soot-blowing or other cleaning device.

My steam generating apparatus will enable the designing engineer to substantially improve the general design of large power stations for it will be feasible to connect my unit directly to a large turbo-generator with its condenser and auxiliaries, thus making a power station comprising a number of large compact generating units and eliminating the costly, complicated and somewhat dangerous system of piping now used in large stations to tie together the multiplicity of boilers, turbines and auxiliary apparatus.

Though I have described with great particularity the construction of the particular steam generating units shown and the method of operating this particular unit, it is not to be construed that I am limited thereto as various changes and modifications may be made without departing from the invention as defined in the appended claims.

What I claim is:

1. A boiler including a drum and a tube bank, a pre-furnace lined with water carrying elements, a main furnace lined with water carrying elements and means for circulating water serially through said tube bank and thence through said water garrflng elements in main furnace and thence to saiddrum, and means for circulating water from said boiler through the water carrying elements in said pre-furnace and thence to said drum. v

2. A boiler including a drum and a tube bank, a main furnace lined with water carrying elements, a pre-furnace lined with water carrying elements, means for circulating water through said tube bank and thence through said water carrying elements in said pre-furnace and thence to said drum, and means for circulating water from said drum through said water carrying elements in said main furnace and said pre-furnace and thence to said drum.

3. A boiler including a drum and a plurality of rows of water carrying tubes'forming a tube bank, the rows of tubes being connected in series by return bends, a pre-furnace lined with water carrying tubes for the absorption of radiant heat, means for circulating water from said drum serially through the rows of tubes forming the tube bank, through the pre-furnace tubes and back to the drum, and means for passing a burning stream of fuel and air downwardly through said furnace and upwardly through said tube bank.

4. A boiler furnace comprising a drum, a tube bank, a plurality of uptake tubes connecting the drum and the tube bank, the uptake tubes forming one wall of the furnace and directly exposed to the heat of the products of combustion, and means for passing a burning stream of fuel and air downwardly past said up-take tubes and then upwardly through said tube bank.

5. A boiler furnace comprising a pre-furnace having walls lined with vertical watercarrying tubes exposed to the heat in the pre-furnace, a main furnace to which the gases from the prefurnace pass, and from which the gases pass to the boiler, said main furnace having walls lined with water carrying and super-heater tubes, a boiler positioned above the main furnace and burners for injecting fuel and air into the main furnace.

6. A boiler furnace comprising a pre-furnace having walls lined with vertical water carrying tubes, means for admitting burning fuel'an'd air to the pre-furnace, a main furnace communicating with and of greater cross-sectional area than the pre-furnace, having walls lined with water carrying and super-heater tubes, the said superheater tubes being exposed to radiant heat and burners adjacent to the super-heater tubes for injecting fuel and air into the main furnace in advance of a boiler above the main furnace.

'7. A boiler furnace comprising a pre-furnace having walls lined with vertical water carrying tubes, means for admitting burning fuel and air to the pre-furnace, a main furnace communicating with the pre-furnace, having walls lined with water carrying tubes and super-heater tubes exposed .to the radiant heat in the main furnace, a boiler positioned at each end of and above the main furnace, and auxiliary means for admitting additional fuel and air into the main furnace adjacent to the super-heater tubes for controllin the degree of super-heat.

8. A boiler furnace comprising a pre-furnace having walls lined with vertical water carrying tubes, means for admitting burning fuel and air to the pre-furnace, a main furnace below and communicating with the pre-furnace having walls lined with water carrying tubes and superheater tubes, the super-heater tubes bent outwardly to form the roof of an oven, means for supplying fuel and air to the oven for controlling the degree of super-heat, the oven having an outlet leading to the main furnace, and a. boiler above the main furnace through which the prodnets of combustion pass from the main furnace.

9. The method of producing steam which comprises creating a stream of ignited combustible gases and air, causing the stream to flow past hot radiating surface, supplying additional air to the stream thereafter, causing the stream to flow in heat exchange relationship with-water while combustion in the stream continues to a substantial extent, permitting the stream to expand, and then passing the stream in heat exchange relationship with water-after combustion is substantially competed.

10. The method of producing steam which comprises creating a stream of ignited, finely divided fuel and air, causing the flaming stream to flow past hot radiating surface, supplying ad ditional air to the stream thereafter, passing the stream in heat exchange relationship with water while combustion in the stream continues to a substantial extent, permitting the stream to expand, and then passing the stream in heat exchange relationship with water after combustion is substantially completed.

11. The method of producing steam which comprises creating a stream of ignited combustible gases and air, causing the stream to flow past hot radiating surface, supplying additional air to the stream thereafter, causing the stream to flow in heat exchange relationship with water While combustion continues in the stream to a substantial extent, thereafter permitting the steam to expand, changing its direction of flow, and passing the stream in heat exchange relationship with water after combustion is substantially completed.

12. The method of producing steam which comprises creating a stream of ignited combustible gases and air, causing the stream to flow past hot radiating surface, supplying additional air to the stream thereafter, causing the stream to flow in heat exchange relationship with water while combustion continues in the stream to a substantial extent, permitting the stream to expand, dividing the stream into lesser streams, and passing each of said lesser stream in heat exchange relationship with water after combustion in said streams is substantially completed.

13. The method of producing steam which comprises creating an ignited stream of finely divided fuel and air, causing the' stream to flow past hot radiating surface, supplying additional air to the stream thereafter, causing the stream to flow in heat exchange relationship with water, while combustion continues in the stream to a substantial extent, permitting the stream to expend, and dividing it into lesser streams, changing the direction of flow of said streams, and then passing the said streams in heat exchange relationship with Water after combustion is substantially completed.

14. The method of producing steam which comprises creating an ignited stream of finely divided fuel and air, causing this stream to flow air, causing the stream to flow past hot radiating surface, supplying additional air to said stream thereafter, causing the stream to flow in heat exchange relationship with water while combustion continues in the stream to a substantial extent, permitting the stream to expand after it has given upon radiant heat to said water, passing the stream in heat exchange relationship with water after combustion in said stream has been substantially completed, extracing additional heat from said stream thereafter by causing air to flow in heat exchange relationship therewith, and utilizing said heated air in creating said ignited stream.

16. The method of producing steam and superheated steam which comprises creating an ignited stream of fuel and air, causing the stream to flow in heat exchange relationship with water while combustion in said stream continues to a substantial extent, creating a second ignited stream of fuel and air, passing said second stream in heat exchange relationship with steam while combustion in said second stream continues to a substantial extent, creating a third stream of ignited fuel and air, passing said third stream in heat exchange relationship with steam while combustion in said stream continues to a substantial extent, uniting the three streams into two streams and causing said streams to flow in heat exchange relationship with water after combustion in said streams has been substantial- 1y completed.

17. The method of producing steam and superheated steam, which comprises creating an ignited stream of fuel and air, exposing water to the radiant heat of combustion of said stream, creating a second ignited stream of fuel and air and exposing steam to the radiant heat of combustion of said second stream, creating a third ignited stream of fuel and air, exposing steam to the radiant heat of combustion of said third stream, uniting the three streams into two streams and causing said two streams to flow separately in heat exchange relationship with water after combustion in said stream has been substantially completed.

18. A furnace wall structure comprising in combination a water wall composed of a block'v of upright tubes exposed to heat within the furnace, a covering carried by said tubes on the outside and a substantially horizontal header outside of the furnace and outside of said covering for 5 of upright tubes exposed to heat within the furnace, a covering carried by said tubes on the outside, a substantially horizontal top header outside of the furnace and outside of said covering from which the water wall is suspended, and a substantially horizontal bottom header for said tubes also outside of the furnace and of said covering.

CHARLES B. GRADY. 

